1. Field of the Invention
The present invention relates generally to a synthetic biologically active composition having a microparticulate core. More particularly, the present invention relates to synthetic, biologically active compositions comprising at least one biologically active peptide, protein or pharmacologic agent attached to a nanocrystalline core particle. The invention further relates to methods of using the resulting synthetic compositions as vaccines, immunodiagnostics or as pharmaceuticals, depending upon the nature of the particular biologically active moiety.
2. Description of Related Art
The attachment of biologically active proteins, peptides or pharmacologic agents to various carrier particles has been an area of intense investigation. These conjugated biological systems offer the promise of reduced toxicity, increased efficacy and lowered cost of biologically active agents. As a result, many different carrier models are presently available. (Varga, J. M., Asato, N., in Goldberg, E. P. (ed.): Polymers in Biology and Medicine. New York, Wiley, 2, 73-88 (1983). Ranney, D. F., Huffaker, H. H., in Juliano, R. L. (ed.): Biological Approaches to the Delivery of Drugs, Ann. N.Y. Acad. Sci., 507, 104-119 (1987).) Nanocrystalline and micron sized inorganic substrates are the most common carriers and proteins are the most commonly conjugated agents. For example, gold/protein (principally immunoglobulin) conjugates measuring as small as 5 nm have been used in immunological labeling applications in light, transmission electron and scanning electron microscopy as well as immunoblotting. (Faulk, W., Taylor, G., Immunochemistry 8, 1081-1083 (1971). Hainfeld, J. F., Nature 333, 281-282 (1988).)
Silanized iron oxide protein conjugates (again principally antibodies) generally measuring between 500 and 1500 nm have proven useful in various in vitro applications where paramagnetic properties can be used advantageously. (Research Products Catalog, Advanced Magnetics, Inc., Cambridge, MA, 1988-1989.) Ugelstad and others have produced gamma iron oxides cores coated with a thin polystyrene shell. (Nustad, K., Johansen, L., Schmid, R., Ugelstad, J., Ellengsen, T., Berge, A.: Covalent coupling of proteins to monodisperse particles. Preparation of solid phase second antibody. Agents Actions 1982; 9:207-212 (id. no. 60).) The resulting 4500 nm beads demonstrated both the adsorption capabilities of polystyrene latex beads as well as the relatively novel benefit of paramagnetism.
Carrier systems designed for in vivo applications have been fabricated from both inorganic and organic cores. For example, Davis and Illum developed a 60 nm system comprised of polystyrene cores with the block copolymer poloxamer, polyoxyethylene and polyoxypropylene, outer coats that showed a remarkable ability to bypass rat liver and splenic macrophages. (Davis, S. S., Illum, L., Biomaterials 9, 111-115 (1988)). Drug delivery with these particles has not yet been demonstrated. Ranney and Huffaker described an iron-oxide/albumin/drug system that yielded 350-1600 nm paramagnetic drug carriers. (Ranney, D. F., Huffaker, H. H., In, Juliano, R. L. (ed.): Biological approaches to the delivery of drugs, Ann. N.Y. Acad. Sci. 507, 104-119 (1987).) Poznasky has developed an enzyme-albumin conjugate system that appears to decrease the sensitivity of the product to biodegradation while masking the apparent antigenicity of the native enzyme. (Poznasky, M. J.: Targeting enzyme albumin conjugates. Examining the magic bullet. In, Juliano, R. L. (ed.): Biological approaches to the delivery of drugs, Annals New York Academy Sciences 1987; 507-211:219.)
Shaw and others have prepared and characterized lipoprotein/drug complexes. (Shaw, J. M., Shaw, K. V., Yanovich, S., Iwanik, M., Futch, W. S., Rosowsky, A., Schook, L. B.: Delivery of lipophilic drugs using lipoproteins. In, Juliano, R. L. (ed.): Biological approaches to the delivery of drugs, Annals New York Academy Sciences 1987; 507:252-271.) Lipophilic drugs are relatively stable in these carriers and cell interactions do occur although little detail is known.
In any conjugated biological composition, it is important that the conformational integrity and biological activity of the adsorbed proteins or other biological agents be preserved without evoking an untoward immunological response. Spacial orientation and structural configuration are known to play a role in determining the biological activity of many peptides, proteins and pharmacological agents. Changes in the structural configuration of these compounds may result in partial or total loss of biological activity. Changes in configuration may be caused by changing the environment surrounding the biologically active compound or agent. For example, pharmacologic agents which exhibit in vitro activity may not exhibit in vivo activity owing to the loss of the molecular configuration formerly determined in part by the in vitro environment. Further, the size and associated ability of the carrier particle to minimize phagocytic trapping is a primary concern when the composition is to be used in vivo. All of these factors must be taken into account when preparing a carrier particle.
Although numerous different carrier particles have been developed, there is a continuing need to provide carrier particles for both in vivo and in vitro application wherein a biologically active peptide, protein or pharmacological agent can be attached to the particles in a manner which promotes stabilization of the biologically active compound in its active configuration. The present invention relates to such particles and compositions.